1) Antianxiety agent 2) Ataractic 3) Ataractic agent 4) Ataractic drug 5) Downer 6) Psychotropic agent 7) Sedative 8) Sedative-hypnotic 9) Sedative-hypnotic drug 10) Tranquilizer 11) Tranquilliser 1) Antipsychotic 2) Neuroleptic 3) Tranquilizer 4) Tranquilliser 
• (n.) One who, or that which, tranquilizes.
(L. tranquillus quiet, calm + -ize verb ending meaning to make + - er agent) a drug with a calming, soothing effect.
tranquillizer (U.S.)
Common name for any drug for reducing anxiety or tension (anxiolytic), such as benzodiazepines, barbiturates, antidepressants, and beta-blockers. The use of drugs to control anxiety is becoming much less popular, because most of the drugs available are capable of inducing dependence